The carbon price is to be introduced into Parliament next month and should be law by the end of the year, the Government has announced.

Climate Change Minister Greg Combet says the Government is keen to get the legislation through both houses of parliament before Christmas so it can stick to its timetable of having it take effect on July 1.

"I'll be bringing the legislation into the House of Reps in September," Mr Combet told Sky News this morning.

But he would not be drawn on questions about the legislation going before parliamentary committees for scrutiny.

"We'll establish the processes in due course within the parliament, but [we want it to get] through the House of Reps and through the Senate this year."

Under the scheme, Australia’s 500 highest-polluting companies will pay $23 for every tonne of carbon pollution they emit from July 1 next year.

Households will get tax cuts and entitlement boosts to offset higher power and other costs.

But the Opposition says it is no foregone conclusion that the bill will pass the House of Representatives, saying one or more Labor members might cross the floor to defeat it.

Nationals Senate leader Barnaby Joyce says not all Labor members believe in the carbon price.

"All we need is one Labor Party lower house member or one of the independents to walk the 10 metres, or 10 feet if they sit at the edge of the gallery, to the other side and the carbon tax will not go through," he told reporters outside Parliament House.

This guy has been running a totally unprincipled, disgraceful campaign.

Greg Combet on Tony Abbott

"I believe in democracy in such a way that people are strong enough to stand by their convictions and stand for what they believe in.

"I've crossed the floor 28 times, I'm still standing here. Yeah, people are not going to talk to you for a couple of years, but you'll get over that."

While Coalition members are not forbidden by their parties to cross the floor, Labor members are, and face certain expulsion from the party if they do break ranks.

Mr Combet also criticised Opposition Leader Tony Abbott for telling his party room yesterday to keep the carbon tax debate civil, saying that it is Mr Abbott himself who is whipping up a fear campaign.

The Opposition Leader made the comments on the same day he addressed an angry anti-carbon tax rally outside parliament.

"One of the most disgusting things in public life I reckon, particularly having spent a lot of my life as a union official, is when you see working people who've had fear instilled in them about their job security and cost of living pressures and the like, [fears] that are totally unjustified.

"I reckon he's just played the most irresponsible role in public policy I've seen for a long time.

"For him to go on to his party room and call for a measured approach, that is the biggest joke I've ever heard."